Table Of Content© The Authors, 2016. Journal compilation © Australian Museum, Sydney, 2016
Records of the Australian Museum (2016) Vol. 68, issue number 5, pp. 231–244.
ISSN 0067-1975 (print), ISSN 2201-4349 (online)
http://dx.doi.org/10.3853/j.2201-4349.68.2016.1663
Two New Species of Quadrisegmentum
(Phtisicidae: Amphipoda: Crustacea)
from the Central Indo-Pacific, with Notes on the
Type Species Q. triangulum Hirayama, 1988
Lauren eLizabeth hughes1* and ichiro takeuchi2
1 Australian Museum Research Institute,
Australian Museum, 1 William Street, Sydney New South Wales 2010, Australia
2 Department of Life Environment Conservation, and Center of Advanced Technology for the Environment,
Faculty of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan
[email protected] · [email protected]
abstract. Two new species of Quadrisegmentum (Phtisicidae: Amphipoda: Crustacea) are described
from the Central Indo-Pacific. The new species Quadrisegmentum atauro sp. nov., is described from the
Wetar Basin, Timor-Leste in the Lesser Sunda Region of the Western Coral Triangle. The new species
name Q. yirrgay sp. nov., is established for material from Ashmore Reef in Queensland and Papua New
Guinea originally reported under the name Q. triangulum Hirayama, 1998 (Guerra-García 2003, 2006;
Guerra-García & Lowry 2009). Study of the type material of Quadrisegmentum triangulum described
from Ashmore Reef in the Timor Sea, Western Australia confirms the absence of projections on pereonite
2, which prompted reassessment of subsequent identifications. Records of Q. triangulum are now limited
to the type locality only. An updated key to the four known species of Quadrisegmentum is provided.
keywords: Quadrisegmentum; new species; Phtisicidae; Amphipoda; Crustacea; taxonomy
hughes, Lauren eLizabeth, and ichiro takeuchi. 2016. Two new species of Quadrisegmentum (Phtisicidae:
Amphipoda: Crustacea) from the Central Indo-Pacific, with notes on the type species Q. triangulum Hirayama, 1988.
Records of the Australian Museum 68(5): 231–244. http://dx.doi.org/10.3853/j.2201-4349.68.2016.1663
Much work remains to be done on the marine amphipod Australian Shelf (Spalding et al., 2007), three previous
fauna of the Central Indo-Pacific. In the Western Coral studies documented 19 species and 15 genera from these
Triangle where the species diversity of coral is the highest two regions combine (Guerra-García, 2003, 2006; Lowry
in the world (Veron et al., 2009), 28 caprellid species from & Guerra-García, 2009).
21 genera have been reported from shallow-waters in the The genus Quadrisegmentum was established by
Indonesian Archipelago (Mayer, 1903; McCain & Steinberg, Hirayama, 1988 to account for one species, Q. triangulum,
1970; Krapp-Schickel & Guerra-García, 2005; Scinto et collected from Ashmore Reef in the Timor Sea. Research
al., 2008). In the Eastern Coral Triangle and Northeast by Guerra-García (2006) described a second species of
* author for correspondence
232 Records of the Australian Museum (2016) Vol. 68
Quadrisegmentum, Q. lowryi Guerra-García, 2006, from absent. Pereonites 6 and 7 separated. Pereopod 3 well
Lizard Island on the northern Great Barrier Reef. Guerra- developed, with 7 articles. Pereopod 4 well developed, with
García (2003, 2006) further reported Q. triangulum from 7 articles. Pereopod 5, with 4 articles, and well-developed
the Lord Howe Island, Elizabeth and Middleton Reef, the dactylus. Pereopods 6 and 7 well developed, with 7 articles.
Great Barrier Reef, Ashmore Reef (Coral Sea) and Papua Gills on pereonites 2 to 4. Uropods 2 pairs; Uropod 1
New Guinea. biarticulate, uniramous. Uropod 2 biarticulate, uniramous.
The present study contributes an additional new species Telson dorsal lobe present.
and generic record, Quadrisegmentum atauro, from Timor-
Included species: Quadrisegmentum triangulum Hirayama,
Leste, which is part of the Lesser Sunda region within the
1988, type species; Q. atauro sp. nov.; Q. lowryi Guerra-
Western Coral Triangle. Quadrisegmentum atauro has
García, 2006; Q. yirrgay sp. nov.
distinct projections of pereonite 2. Comparative examination
of Q. triangulum type material confirmed the absence of Remarks. Characters which define the family Phtisicidae
projections on pereonite 2, yet in material subsequently Vassilenko, 1968 are a fully fused head and pereonite 1,
attributed to Q. triangulum (see Guerra-García, 2003, 2006), absence of a mandibular molar and 3-articulate palp, gills
pereonite 2 projections were observed on male and female on pereonites 2–4 (3 pair), pereonites 5 and 6 separated
species from various locations. Following reassessment and the urosomites 1 and 2 coalesced (see Takeuchi, 1993,
of the latter material, a second new species Q. yirrgay, is 2015; Lim et al., 2012; Takeuchi and Lowry, 2016). The
established for previous records of Q. triangulum reported diagnosis of the genus was based observations of the type
throughout the Coral Sea and Bismark Archipelago (Eastern material of Q. triangulum Hirayama, 1988 by the present
Coral Triangle and Northeast Australian Shelf, respectively). study with reference to description and figures of mouth parts
in Hirayama (1988) and additionally the two new species
Materials and methods described in the current study, Q. atauro sp. nov. and Q.
yirrgay sp. nov. (map Fig. 11) provides the distribution of
The material examined for this study included type
the four known Quadrisegmentum species.
material from the Museum and Art Gallery of the Northern
Territory (NTM), Australian Museum (AM) collections of
Quadrisegmentum and new collections made during the
Quadrisegmentum atauro sp. nov.
Australian Museum Timor-Leste Expedition in September
2012 (Hughes, 2015). Material was dissected in 80%
Figs 1–4
ethanol. Temporary slides were made using 100% glycerol.
Permanent slides were made using either Polyvinyl
Type material. Holotype ♂, 10.5 mm (illustrated), dissected in part, 1 slide,
lactophenol or AquatexTM (Merck, Darmstadt, Germany) AM P.98327, Timor-Leste, east of Atauro Island, Outer Reef, dense coral
mounting agent. Illustrations were made with a Laborlux K reef slope (8°13'48"S 125°36'57"E), 17 m, green calcareous alga Halimeda
(Leitz Wetzlar, Germany) and Heerbrugg stereomicroscopes sp., 20 September 2012, coll. L.E. Hughes (TM 2012-087); paratype
♀, 9 mm (illustrated), AM P.98328, Timor-Leste, east of Atauro Island,
(Wilde, Switzerland) fitted with camera lucida. Specimens
Outer Reef, dense coral reef slope (8°13'48"S 125°36'57"E), 17 m, green
were prepared for scanning electron microscopy as follows: calcareous alga Halimeda sp., 20 September 2012, coll. L.E. Hughes (TM
placed in an ultrasonic cleaning bath for 10 seconds in a 10% 2012-087). Paratypes: 1 ♂, 5.1 mm [a smaller specimen has been chosen
solution of Tween 80 surfactant; preserving solution was for SEM as it is in better condition], whole animal SEM pin mount, AM
P.91095, Timor-Leste, east of Atauro Island, Outer Reef, dense coral reef
returned to 80% ethanol then sequentially advanced in 5%
slope (8°13'48"S 125°36'57"E), 17 m, green calcareous alga Halimeda sp.,
increments from 80% to 100% ethanol; critical point dried;
20 September 2012, coll. L.E. Hughes (TM 2012-087); 1 ♂, 10.5 mm, SEM
mounted individually on pins and gold sputter coated. Images pin mount, AM P.91091, Timor-Leste, east of Atauro Island, Outer Reef,
were captured using on a Zeiss EVO LS15 Scanning Electron dense coral reef slope (8°13'48"S 125°36'57"E), 17 m, green calcareous
Microscope with Robinson Backscatter Detector (SEM) alga Halimeda sp., 20 September 2012, coll. L.E. Hughes (TM 2012-087);
3 ♂♂, AM P.91097, Timor-Leste, east of Atauro Island, Outer Reef, dense
(Zeiss, Germany). Abbreviations for parts are as follows:
coral reef slope (8°13'48"S 125°36'57"E), 17 m, green calcareous alga
A, antenna; G, gnathopod; P, pereopod and Ur, urosome. Halimeda sp., 20 September 2012, coll. L.E. Hughes (TM 2012-087); 1 ♂,
Family classification follows Takeuchi (1993). AM P.91092, Timor-Leste, east of Atauro Island, Outer Reef, dense coral
reef slope (8°13'48"S 125°36'57"E), 17 m, green calcareous alga Halimeda
sp., 20 September 2012, coll. L.E. Hughes (TM 2012-087); 1 mature ♀, AM
Systematics section P.91096, Timor-Leste, east of Atauro Island, Outer Reef, dense coral reef
slope (8°13'48"S 125°36'57"E), 17 m, green calcareous alga Halimeda sp.,
20 September 2012, coll. L.E. Hughes (TM 2012-087); many specimens,
Phtisicidae Vassilenko, 1968
AM P.91094, Timor-Leste, east of Atauro Island, Outer Reef, dense coral
reef slope (8°13'48"S 125°36'57"E), 17 m, green calcareous alga Halimeda
Quadrisegmentum Hirayama, 1988 sp., 20 September 2012, coll. L.E. Hughes (TM 2012-087); 4 mature ♀♀,
AM P.91093, Timor-Leste, east of Atauro Island, Outer Reef, dense coral
Diagnosis. Head fused (suture absent) with pereonite 1. reef slope (8°13'48"S 125°36'57"E), 17 m, green calcareous alga Halimeda
Antenna 1 well developed; flagellum with more than 2 sp., 20 September 2012, coll. L.E. Hughes (TM 2012-087); 7 specimens
(6 ♂♂ and 1 mature ♀), AM P.91090, Timor-Leste, east of Atauro Island,
articles. Antenna 2 well developed; flagellum with more
Inner Reef, reef slope (8°14'30"S 125°36'49"E), 14 m, mixed turfing algae,
than 2 articles. Mandible well developed; molar absent; 20 September 2012, coll. L.E. Hughes (TM 2012-034); 1 mature ♀, AM
palp 3-articulate; article 3 with 1 distal and 1 (or 2) lateral P.91099, Timor-Leste, west of Dili, off Tibar, on outer side of reef, rubble
setae. Maxilliped well developed; inner plate (basal endite) and sandy reef slope (8°33'48"S 125°28'31"E), 10–12 m, coral rubble
and mixed algae, 21 September 2012, coll. A. Murray (TM 2012-037); 9
larger than outer plate (ischial endite); outer plate (ischial
specimens (5 ♂♂ and 4 mature ♀♀), AM P.91098, Timor-Leste, east of
endite) well developed; palp article 3 with distal projection;
Metinaro, Secret Garden Reef (8°29'15"S 125°49'53"E), 20 m, tufts of red
palp article 4 well developed. Pereonite 4 clavate appendage algae, 22 September 2012, coll. L.E. Hughes (TM 2012-060).
Hughes & Takeuchi: New Quadrisegmentum amphipods 233
Figure 1. Quadrisegmentum atauro sp. nov., holotype
male habitus, 10.5 mm, AM P.98327 and paratype
female, 9 mm, AM P.98328; Atauro Island, Timor-Leste.
Figure 2. Quadrisegmentum atauro sp. nov. holotype
male, 10.5 mm, AM P.98327, Atauro Island, Timor-
Leste, scales 0.1 mm.
234 Records of the Australian Museum (2016) Vol. 68
Figure 3. Quadrisegmentum atauro sp. nov. holotype male, 10.5
mm, AM P.98327, Atauro Island, Timor-Leste, scales 0.1 mm.
Type locality. Timor-Leste, east of Atauro Island, Outer Reef Body Somites slender. Head and pereonite 1 combined,
(8°13'48"S 125°36'57"E). completely fused, suture absent. Pereonite 2 with small acute
anterolateral projection. Pereonites 3–6 without anterior or
Etymology. Named from the type locality, applied as a noun
mid-lateral projections.
in apposition.
Antenna 1 ⅓× body length; peduncle article 2 longest,
Description. (Based on male, body length, 10.5 mm, AM 1.9× article 1; article 3 length 0.8× article 2; flagellum length
P. 98327, and male, body length, 10.5 mm, AM P.91901 for 0.24× peduncle with 4–6 articles (left and right, respectively).
pereopod 5 and abdomen). Antenna 2 0.9× Antenna 1; flagellum, 0.25× peduncle length,
body with 8–9 articles (left and right, respectively).
Hughes & Takeuchi: New Quadrisegmentum amphipods 235
Figure 4. Quadrisegmentum atauro sp. nov. SEM image of paratype male, 5.1 mm, head and pereopod 4, AM P.91095; paratype male,
10.5 mm, gnathopod 2, pereopod 5 and urosome paratype male AM P.91091; Atauro Island, Timor-Leste. Scales: H and P4–5 scale 100
µm, Ur dorsal view scale 10 mm and Ur transverse view 20 µm.
Mandible right similar to left, incisor with 4 teeth, lacinia slender setae. Maxilla 2 inner plate short with 4 robust setae;
mobilis with 7 teeth followed by 2 plates; palp 3-articulate; outer plate long, with 4 apical and 1 subapical robust setae.
article 2 longest, with 1 distal slender setae; article 3 with Maxilliped basal endite (inner plate) larger than ischial endite
1 distal and 1 midlateral slender setae, anterodistal margin (outer plate), rectangular, with 4 apically robust setae near
pub es cent. Mandible left, palp similar to right palp. Lower distal margin; ischial endite (outer plate) several slender
lip setose on outer lobe. Maxilla 1 outer plate with 5–6 setae on inner margin; palp 4-articulate; article 2 laterally
robust setae; palp 2-articulate, article 2 with 2 triangular expanded, with 3–4 slender setae; article 3 with rounded
projections, each with a robust seta, with 3–4 subapical distal projection with 2 setae.
236 Records of the Australian Museum (2016) Vol. 68
Pereon. Gnathopod 1 basis similar in length to ischium, Quadrisegmentum triangulum Hirayama, 1988
merus and carpus combined; carpus and merus subequal in
length with anterior and posterior slender setae; propodus Fig. 5
triangular; palm defined by prominent, curved, bifid process
Quadrisegmentum triangulum —Hirayama, 1988: 1090–
with 2 apical robust setae; dactylus falcate, inner margin
1093, figs. 1–3.
lined with setules. Gill 2 elongate, length 5× width, 0.6× not Quadrisegmentum triangulum. —Guerra-Garcia, 2003:
pereonite 2 length. Gnathopod 2 begins ⅓ along posterior 104–105, fig. 9a. —Guerra-Garcia, 2006: 440, fig. 39.
margin of pereonite 2; basis length 1.9× pereonite 2 —Guerra-Garcia & Lowry, 2009: 323–325 (= Q. yirrgay
length, 1.6× ischium, merus and carpus combined; merus sp. nov.).
subrectangular, distally swollen (length 2.8× width),
Type material examined. Paratypes 1 ♂ (no. 1) 8 mm,
subequal to carpus; carpus subrectangular (length 3.1×
and 2 ♀♀ (nos. 2–3) 5.2 mm and unmeasured, NTM Cr.
width); propodus subovate, longer than wide (length
00447, taken from gorgonian host, Isis hippuris Linnaeus,
2.8× width); palm 60% of posterior margin, 3 proximal
1758 in 18 m on west islet of Ashmore Reef, Northwest
projections each with robust seta.
Australia (12°14.28'S 122°59.14'E.), 24 July 1986, coll. H.
Gill 3 slender, 7× width, length 0.9× pereonite 3 length.
K. Larson. (Holotype carcass and slide material not found,
Pereopod 3 length 0.3× body length; basis longest, 0.4×
presumed lost).
pereopod 3 length; ischium 0.1× basis length; merus
0.6× basis length; carpus 0.27× basis length; propodus Type locality. Ashmore Reef, Timor Sea, north-west Western
0.9× carpus length with 3 large and 1 small robust setae Australia (12°14.28'S 122°59.14'E).
along palm; dactylus recurved. Gill 4 subequal to gill 3.
Remarks. Examination of Q. triangulum type material
Pereopod 4 shorter than pereopod 3, length 0.35× body
recognizes the absence of projections on pereonite 2 in
length; basis longest, 0.4× pereopod length; ischium 0.06×
both sexes and also records the presence of anterolateral
basis length; merus 0.65× basis length; carpus 0.3× basis
projections on the male pereonite 3. These anterolateral
length; propodus shorter than carpus, length 0.9× carpus
projections on pereonite 3 were not recorded in the original
with 3 large and 1 small robust setae along palm; dactylus
description by Hirayama (1988). Additional material
recurved.
attributed to Q. triangulum by the first and second reviewer
Pereopod 5 with 4 articles; article 1 length 0.9× article 2;
from Queensland, Australian and Papua New Guinea
article 2 longest, 1.1× article 3; dactylus recurved. Pereopod
(Guerra-García, 2003, 2006), contained specimens where
6 slender, 0.5× body length; basis longest, 0.37× pereopod
pereonite 2 projections were observed on males and females.
6 length; ischium 0.08× basis length; merus 0.7× basis
This latter material was reassessed as part of this study
length; carpus 0.33× basis length, anterior margin with 2
and determined to be a separate species. These records are
robust setae; propodus 0.6× basis length, anterior margin
transferred to the new species name Q. yirrgay described
with 3 groups of long robust setae (middle group only with
below. The name Quadrisegmentum triangulum is once again
paired robust setae) and distal small robust setae; dactylus
restricted to the original type material and presently known
recurved. Pereopod 7 slender, smaller than pereopod 6, 0.4×
only from the type locality.
body length; basis 0.27× pereopod 7 length; ischium 0.25×
basis length; merus length subequal to basis; carpus 0.65× Distribution. Ashmore Reef (Hirayama, 1988).
basis length, anterior margin with 2 robust setae; propodus
0.8× basis length, anterior margin with 3 groups of long
robust setae (middle group only with paired robust setae)
Quadrisegmentum yirrgay sp. nov.
and distal small robust setae; dactylus recurved.
Figs 6–10
Pleon. Uropod 1 elongate (length 6× width), with minute
a line of lateral setae; ramus damaged. Uropod 2 peduncle Quadrisegmentum triangulum. —Guerra-Garcia, 2003:
elongate (length 2.5× width), with a line of lateral setae; 104–105, fig. 9a. —Guerra-Garcia, 2006: 440, fig. 39.
ramus 0.6× peduncle length. Telson small, with a pair of —Guerra-Garcia & Lowry, 2009: 323–325.
setae.
Type material. Holotype ♂ 9.0 mm, AM P.98563, outer reef slope, Ashmore
Female. (based on female paratype, body length 9 mm, Reef, Coral Sea, Queensland, Australia (10°26'16"S 144°25'47"E), red
calcareous cylindrical algae, 19 January 1993, coll. S.J. Keable (QLD 704);
AM P. 98328). Pereonite 4 without rounded anterolateral
paratype ♂ 9.0 mm, AM P.98564, outer reef slope, Ashmore Reef, Coral Sea,
projection. Antenna 1 article 2 subequal to article 3 length,
Queensland, Australia (10°26'16"S 144°25'47"E), red calcareous cylindrical
1.8× article 1 length; flagellum with 10 articles. Antenna 2 algae, 19 January 1993, coll. S.J. Keable (QLD 704); many specimens, AM
near 2/3 length of antenna 1; flagellum 0.6× peduncle length P.61630, outer reef slope, Ashmore Reef, Coral Sea, Queensland, Australia
with 7 articles. (10°26'16"S 144°25'47"E), red calcareous cylindrical algae, 19 January
1993, coll. S.J. Keable (QLD 704). Paratypes: ♀, 6 mm, AM P.61624, eastern
edge of outer reef slope, Ashmore Reef, Coral Sea, Queensland, Australia
Remarks. Quadrisegmentum atauro sp. nov. and Q. yirrgay
(10°09'10"S 144°34'43"E) calcareous red tubular algae, 24 January 1993,
sp. nov. have long rectilinear gills which separates them coll. S.J. Keable (QLD 734); 2 specimens (1 ♂ and 1 ♀), AM P.61627,
from Q. triangulum where the gills are much shorter and eastern edge of outer reef slope Ashmore Reef, Coral Sea, Queensland,
subovate. The pereonite 2 in Q. atauro sp. nov. has on one Australia (10°09'10"S 144°34'43"E) mixed sponges, 24 January 1993, coll.
pair of acute anterior lateral projections which are not seen S.J. Keable (QLD 736); 4 specimens (2 ♂♂ and 2 ♀♀), AM P.61629, outer
reef slope, Ashmore Reef, Coral Sea, Queensland, Australia (10°13'10"S
for Q. yirrgay sp. nov. and Q. lowryi Guerra-García, 2006.
144°24'53"E) sponges, 22 January 1993, coll. S.J. Keable (QLD 722); 1
♂, AM P.61625, outer reef slope, Ashmore Reef, Coral Sea, Queensland,
Distribution. Timor-Leste: Atauro Island, Tibar (current Australia (10°26'16"S 144°25'47"E) sediment, algae and rubble, 19 January
study). 1993, coll S.J. Keable (QLD 705).
Hughes & Takeuchi: New Quadrisegmentum amphipods 237
Figure 5. Quadrisegmentum triangularum Hirayama, 1988 paratypes male habitus 8 mm
and female habitus 5.2 mm, Ashmore Reef, Timor Sea, north-west Western Australia.
Additional material examined. Australia. Queensland: 5 specimens (1
♂ and 4 ♀♀), AM P.32302, off Mangrove Beach, Lizard Island (14°40'S
145°28'E), 2 m, mixed algae from bommie, 28 September 1978, coll. J.K.
Lowry (QLD 1); 2 specimens (1 ♂ and 1 ♀), AM P.32314, off southern Point October 1978, coll. P.C. Terrill (QLD 52); 1 ♂, AM P.61626, Great Barrier
of Mermaid Cove, Lizard Island (14°39'S 145°27'E), 3–6.1 m, filamentous Reef, inside outer barrier, Lizard Island (10°34'29"S 143°55'17" E), 15 m,
algae with stone washings and scrapings from crevices, 8 October 1978, rubble, 16 January 1993, coll. S.J. Keable (QLD 682); 1 ♂, AM P.61712,
coll. C. J. Short & P.C. Terrill (QLD–25); 1 ♀, AM P.32318, fringing reef between Palfrey Island and Lizard Island, western side of Blue Lagoon,
between Bird Islet and South Island, Lizard Island (14°40'S 145°28'E), Lizard Island (14°41'S 145°27'E), 7 October 2001; 5 specimens (2 ♂♂ and
25 m, green algae Halophila sp. and mixed algae from grass beds off reef 3 ♀♀), AM P.61713, between Palfrey Island and Lizard Island, western
base, 9 October 1978, coll. J.K. Lowry (QLD 29); 2 ♂♂, AM P.32320, side of Blue Lagoon, Lizard Island (14°41'S 145°27'E), 7 October 2001;
reefs at western end of Blue Lagoon, Lizard Island (14°40'S 145°28'E), 3 1 ♀, AM P.61714, between Palfrey Island and Lizard Island, western side
m, sand near artificial reefs, 5 October 1978, coll. P.C. Terrill (QLD 33); of Blue Lagoon, Lizard Island (14°41'S 145°27'E), 2–3 m, coral rubble,
16 specimens (6 ♂♂, 9 ♀♀, 1 juvenile), AM P.32325, Mermaid Cove, 7 October 2001, coll. J.M. Guerra-García & S.J. Keable (QLD 1469); 8
Lizard Island (14°40'S 145°28'E), subtidal to 2 m, mixed algae, coral specimens (4 ♂♂ and 4 ♀♀), AM P.61715, Coconut Beach, Lizard Island
rubble and silt, 14 October 1978, coll. J.K. Lowry (QLD–48); 1 ♀, AM (14°41'S 145°27'E), 6 m, fine live hard coral encrusted with calcareous red
P.32326, off North Point, Lizard Island (14°39'S 145°27'E), 3–6.1 m, red algae and filamentous red/green/brown algal turf, 8 October 2001, coll.
algae (Galaxaura sp.) and coral rubble from subtidal caves, 14 October J.M. Guerra-García & S.J. Keable (QLD 1476); 3 specimens (1 ♀ and 2
1978, coll. J.K. Lowry (QLD 49); 9 specimens (7 ♂♂, 1 ♀, 1 juvenile), juveniles), AM P.61716, Crystal Beach, Lizard Island (14°41'S 145°27'E),
AM P.32327, off North Point, Lizard Island (14°39'S 145°27'E), 3–6.1 m, 5 m, thick branching coral rubble encrusted with red algal turf and black
mixed algae, 14 October 1978, coll. J.K. Lowry (QLD 50); 7 specimens sponge half buried in sediment, 9 October 2001, coll. J.M. Guerra-García
(4 ♂♂ and 3 ♀♀), AM P.32328, Lizard Island, off North Point, Lizard & S.J. Keable (QLD 1483); 1 juvenile, AM P.61717, Crystal Beach, Lizard
Island (14°39'S 145°27'E), 6.1 m, green calcareous alga Halimeda sp., 14 Island (14°41'S 145°27'E), 4 m, thin branching live coral heavily encrusted
238 Records of the Australian Museum (2016) Vol. 68
Figure 6. Quadrisegmentum yirrgay sp. nov., holotype male habitus, 9.0 mm, AM P.98563;
paratype female, 6 mm, AM P.61624, Ashmore Reef, Coral Sea, Queensland, Australia.
with brown/green algal turf and red calcareous algae, 9 October 2001, coll.
J.M. Guerra-Garcia & S.J. Keable (QLD 1485); 5 specimens (2 ♂♂ and 3
♀♀), AM P.61718, Chinamans Ridge, Lizard Island (14°41'S 145°27'E),
2 m, brown alga Padina cf. gymnospora from reef, 11 October 2001,
coll. J.M. Guerra-Garcia & S.J. Keable (QLD 1524); 1 ♀, AM P.61719,
north–west edge of Palfrey Island, Lizard Island (14°41'S 145°27'E), 3 m,
green calcareous alga Halimeda micronesia Yamada, 1941 and Halimeda
macroloba Decaisne 1841, 12 October 2001, coll. J.M. Guerra-Garcia & S.J.
Keable (QLD 1526); 2 specimens (1 ♂ and 1 immature ♀), AM P.61720,
north–west edge of Palfrey Island, Lizard Island (14°41'S 145°27'E), 12
m, dead whip coral (Junceella sp.) heavily encrusted with red algal turf
and calcareous red algae, 12 October 2001, coll. J.M. Guerra-Garcia & S.J.
Keable (QLD 1528); 2 ♀♀, AM P.61721, Blue Lagoon between Bird Islet
and South Island, Lizard Island (14°41'S 145°27'E), 2 m, mixed encrusted
coral rubble, 13 October 2001, coll. J.M. Guerra-Garcia & S.J. Keable
(QLD 1536); 1 ♂, AM P.61722, reef slope on south side of South Island,
Lizard Island (14°41'S 145°27'E), 20 m, gorgonian (cf. Paracis sp.), 14
October 2001, coll. J.M. Guerra-Garcia & S.J. Keable (QLD 1541); many
specimens, AM P.61723, reef slope on south side of South Island, Lizard
Hughes & Takeuchi: New Quadrisegmentum amphipods 239
Figure 7. Quadrisegmentum yirrgay sp. nov., holotype male 9.0 mm, AM
P.98563, Ashmore Reef, Coral Sea, Queensland, Australia, scales 0.1 mm.
Island (14°41'S 145°27'E), 25 m, gorgonian (cf. Menella sp.), 14 October (Site 12); 1 ♂, AM P.61582, The Sound, large alcove near lagoon entrance,
2001, coll. J.M. Guerra-Garcia & S.J. Keable (QLD 1544); 1 ♂, AM Middleton Reef, Elizabeth and Middleton Reefs (29°27'42"S 159°05'24"E),
P.61724, reef slope on south side of South Island, Lizard Island (14°41'S rubble wash, 5 December 1987 (Site 7); 1 ♂, AM P.61475, reef front
145°27'E), 20 m, gorgonian (cf. Mopsella sp.), 14 October 2001, coll. J.M. south of North Passage, straight out from Signal Point, Lord Howe Island
Guerra-Garcia & S.J. Keable (QLD 1545); 2 ♂♂, AM P.61725, north–east (31°31'36"S 159°03'E) coralline algae, coll. G.D. Fenwick, 11 May 1977
side of Lizard Island, reef slope south of "Washing Machine" (14°41'S (LHA 17).
145°27'E), 18 m, brown sponge cf. Clathria reinwardti, 16 October 2001, Papua New Guinea: ♂ 6.1 mm, whole animal SEM pin mount, AM
coll. J.M. Guerra-Garcia & S.J. Keable (QLD 1565); 1 ♀, AM P.61726, P.97779, The Quarry, near the village of Bunu 2, Madang (4°46'30"S
north–east side of Lizard Island, reef slope south of "Washing Machine" 145°48'E), coral slope with rubble, sand, ascidian Didemnum molle
(14°41'S 145°27'E), 6 m, green calcareous alga Halimeda macroloba, 16 (Herdmann, 1886) and sponges, 21 January 1990, coll. J.K. Lowry (PNG
October 2001, coll. J.M. Guerra-Garcia & S.J. Keable (QLD 1568); 1 ♀, 69); ♀ 6.1 mm, AM P.98565, The Quarry, near the village of Bunu 2,
AM P.61727, north–east side of Lizard Island, reef slope south of "Washing Madang (4°46'30"S 145°48'E), coral slope with rubble, sand, ascidian
Machine" (14°41'S 145°27'E), 5 m, sediment with green alga Halimeda Didemnum molle and sponges, 21 January 1990, coll. J.K. Lowry (PNG
cylindracea Decaisne 1842, Udotea and Caulerpa spp., 16 October 2001, 69); 3 specimens (2 ♂ and 1 mature ♀), AM P.61534, base of reef slope,
coll. J.M. Guerra-Garcia & S.J. Keable (QLD 1569); 2 specimens (1 ♂ and outer face, Horseshoe Reef, Bootless Inlet (9°30'30"S 147°15'30"E) green
1 juvenile), AM P.61728, north–east side of Lizard Island, reef slope south calcareous alga Halimeda opuntia (Linnaeus) J.V. Lamouroux 1816, 28
of "Washing Machine" (14°41'S 145°27'E), 6 m, mixed silty filamentous October 1980, coll. S.P. Arnam & J.K. Lowry (PNG-23); 1 mature ♀,
red algae and green alga Caulerpa taxifolia (M.Vahl) C.Agardh 1817, 16 AM P.61533, Horseshoe Reef, Bootless Inlet (9°30'30"S 147°15'30"E)
October 2001, coll. J.M. Guerra-Garcia & S.J. Keable (QLD 1573); 1 ♂, coral rubble from reef front slope, 29 October 1980, coll. S.P. Arnam &
AM P.61729, Pidgin Point, Lizard Island (14°41'S 145°27'E), 20 m, sponge J.K. Lowry (PNG-32); 1 ♂, AM P.61536, Horseshoe Reef, Port Moresby
cf. Clathria reinwardti, 18 October 2001, coll. J.M. Guerra-Garcia & S.J. (9°36'30"S 147°17'54"E) gorgonian, 2 November 1980, coll. A.J. Bruce
Keable (QLD 1581); 1 ♂, AM P.61730, reef just south–west of Osprey (AJB 206); 4 specimens (3 ♂♂ and 1 damaged juvenile), AM P.61537,
Island, Lizard Island (14°41'S 145°27'E), 10–12 m, fine–medium sand with Lion Island, Manunouma Islands (9°32'17"S 147°06'13"E), gorgonian,
some shell, 18 October 2001, coll. J.M. Guerra-Garcia & S.J. Keable (QLD 5 November 1980, coll. A.J. Bruce (AJB-208); 4 specimens (3 ♂♂ and 1
1588); 1 mature ♀, AM P.61731, Granite Bluff, Lizard Island (14°40'S mature ♀), AM P.61535, outside Horseshoe Reef, Bootless Inlet (9°30'30"S
145°28'E), reef rock, 30 August 1976, coll. P.A. Hutchings (25–1); 4 ♂♂, 147°17'30"E), crinoids from outer reef face, 9 November 1980, coll. S.P.
AM P.61732, northern end of Mermaid Beach, Lizard Island (14°41'S Arnam & J.K. Lowry (PNG-63); 74 specimens, AM P.61531, The Quarry,
145°27'E), 4 m, brown alga Padina sp., 12 October 2001, coll. J.M. Guerra- near the village of Bunu 2 (4°46'30"S 145°48'E), coral slope with rubble,
Garcia & S.J. Keable (QLD 1533). sand, ascidian Didemnum molle and sponges, 21 January 1990, coll. J.K.
Tasman Sea: 7 specimens (6 ♂♂ and 1 ♀), AM P.61581, patch reef Lowry (PNG 69); 1 ♂, AM P.61532, The Quarry, near the village of Bunu
in lagoon, Middleton Reef, Elizabeth and Middleton Reefs (29°27'36"S 2 (4°46'30"S 145°48'E), coral slope with rubble, sand and black sponge,
159°06'42"E), prolific coral cover on top of bommie, 6 December 1987 coll. J.K. Lowry, 21 January 1990 (PNG 68).
240 Records of the Australian Museum (2016) Vol. 68
Figure 8. Quadrisegmentum yirrgay sp. nov., holotype male 9.0 mm,
AM P.98563, Ashmore Reef, Coral Sea, Queensland, Australia, scales
0.1 mm.
Antenna 1 more than ⅓× body length (broken); peduncle
article 2 longest, 2× article 1; article 3 length 0.8× article 2;
flagellum with more than 4 articles (broken).
Upper lip weakly notched. Mandible right, incisor with
4 teeth, lacinia mobilis with 5 teeth followed by 2 plates;
palp 3-articulate; article 2 longest; article 3 with 1 distal and
2 midlateral slender setae, anterodistal margin pubescent.
Mandible left, incisor with 5 teeth, lacinia mobilis followed
by 2 plates; Lower lip setose on outer lobe. Maxilla 1 outer
plate with 6 robust setae; palp 2-articulate, article 2 with 3
long and 2 short robust seate. Maxilliped basal endite (inner
plate) larger than ischial endite (outer plate), basal endite with
3 apically serrate robust setae; ischial endite (outer plate)
margin with several slender setae; palp 4-articulate; article
2 lateral expanded, with 5 setae; article 3 with sub-triangular
distal projection.
Type locality. Ashmore Reef, off Great Barrier Reef, Coral
Pereon. Gnathopod 1 basis similar in length to ischium,
Sea, Queensland, Australia (10°26'16"S 144°25'47"E). (The
merus and carpus combined; carpus subequal to merus
present “Ashmore Reef” is the different “Ashmore Reef”,
length, posterior margin with slender setae; propodus
Timor Sea, north-west Western Australia, type locality for
triangular; palm defined by prominent, curved, bifid process
Q. triangulum)
with 2 apical robust setae; dactylus falcate, inner margin
Etymology. “Yirrgay” is the lost spoken language of a lined with setules. Gill 2 subovate, length 0.6× pereonite
coastal indigenous group in Far North Queensland. Applied 2 length. Gnathopod 2 begins ⅓ along posterior margin
as a noun in apposition. of pereonite 2; basis length 1.4× pereonite 2 length, 2.1×
ischium, merus and carpus combined; merus subrectangular,
Description. (Based on holotype ♂, body length 9.0mm, AM
distally swollen (length 2× width), longer than to carpus;
P.98563 and male, body length, 6.1 mm, SEM AM P.97779
carpus subrectangular (length 2× width); propodus subovate,
for abdomen).
longer than wide (length 2.1× width); palm 60% of posterior
Body Somites sub-slender. Head and pereonite 1 combined, margin, 3 proximal projections each with robust seta.
completely fused, suture absent, with pair of apically Gill 3 elongate, length 0.6× pereonite 3. Pereopod 3
truncate dorsodistal projections. Pereonite 2, with small basis longest, 0.4× pereopod 3 length; ischium 0.1× basis
acute anterolateral projection and larger acute mid lateral length; merus 0.7× basis length; carpus 0.25× basis length;
projection. Pereonite 3, with minute mid-lateral projection. propodus 1.1× carpus length with 2 large robust setae along
Pereonites 4–6 without anterior or mid-lateral projections palm, dactylus recurved. Gill 4 subequal to gill 3. Pereopod
